FIG. 1 is a flowchart of a conventional video delivery pipeline 100 showing various stages from video capture to video content display. A sequence of video frames 101 is captured at block 102. Video frames 101 may be digitally captured (e.g. by a digital camera) or generated by a computer (e.g. using computer animation) to provide a stream of video data 103. Alternately, video frames 101 may be captured on film by a film camera. The film is converted to a digital format to provide a stream of video data 103.
Video data 103 is provided to a processor at block 104 for post-production editing. Block 104 post-production editing may include adjusting or modifying colors or brightness in particular areas of an image to enhance the image quality or achieve a particular appearance for the image in accordance with the video creator's creative intent. Other editing (e.g. scene selection and sequencing, image cropping, addition of computer-generated visual special effects, etc.) may be performed at block 104. During block 104 post-production editing, video images are viewed on a reference display.
Following post-production, video data 103 is delivered at block 106 to a display subsystem. As seen in FIG. 1A, block 106 delivery includes an encoder stage 107A for driving broadcast or transmission of video data 103 over a video distribution medium 105 (e.g. satellite, cable, DVD, etc). A decoder stage 107B is located at the display end of block 106 to decode video data 103 transmitted over medium 105. The display subsystem may include a video processor and a display. At block 108, video data 103 is provided to the video processor for processing and/or decoding. Video data 103 is output to the display at block 110 to display a sequence of images to a viewer.
To improve the quality of the displayed images, video data 103 may be driven through video delivery pipeline 100 at a relatively high bit rate so as to facilitate an increased bit depth for defining RGB or chroma values for each chrominance (color) channel. For example, a stream of video data 103 may comprise 8, 10 or 12 bits of data for each chrominance channel of a pixel. In other embodiments, a stream of video data 102 may comprise more than 12 bits of data for each chrominance channel of a pixel.
Despite using a high bit depth for each chrominance channel, variations in display characteristics (such as luminance range, gamut, etc.) may affect the appearance of an image rendered on a display so that the image rendered does not match the creative intent of the video's creator. In particular, the perceived color or brightness of an image rendered on a particular display subsystem may differ from the color or brightness of the image as viewed on the reference display during block 104 post-production editing.
Moreover, methods applied at processing or display stages of a conventional video delivery pipeline, such as those stages represented by blocks 104, 108 and 110 of video delivery pipeline 100 (FIG. 1), are typically performed in a pre-configured manner without taking into account processing which may have occurred at other stages of video delivery pipeline 100. For example, the block 110 methods for displaying video data 103 may be performed without knowledge of how prior processing steps in video delivery pipeline 100 were carried out, such as block 104 post-production editing. The block 110 display methods may not be suitable for rendering an image on the display in a manner which preserves the video creator's creative intent, as determined by block 104 post-production editing.
There is a general desire for systems, apparatus and methods for generating, delivering, processing and displaying video data to preserve the video creator's creative intent. There is a general desire for systems, apparatus and methods for providing information which may be used to guide downstream processing and/or display of video data.